Abstract
The authors have previously reported a method of decerebration of the dog by means of cephalic vascular stasis. 1 The emphasis at that time was upon the use of the procedure as a method for preparing decerebrate animals. Since that time our interest has shifted to the evidence that could be gained concerning the resistance of various cells in the brain to temporary cessation of blood flow and the correlation of these changes with changes in the behavior of the animal.
The technic has been modified to the following form: Two days after laminectomy at the second cervical level, the animal is atropinized, and a metal tracheal tube is inserted orally. A blood pressure cuff is wrapped about the neck, and the pressure is raised quickly to 700 mm Hg, at which level it is maintained as long as vascular arrest is desired, artificial respiration being administered through the tracheal tube. The completeness of circulatory arrest in the head is determined by ophthalmoscopic examination of the retinal vessels. With this technic, consciousness is lost in a very few seconds, the corneal reflex disappears in from 20 to 40 seconds, and spontaneous respiration ceases in from 40 to 90 seconds.
In 6 adult animals there was complete cessation of cephalic blood flow for periods of from 2 to 10 minutes. In the dogs subjected to 8 minutes or less of compression the lid wink returned in 5 to 8 minutes; in 2 animals treated for 10 minutes it did not return till later. The first gasp occurred in 1 to 5 minutes and satisfactory spontaneous respiration returned in 2 to 11 minutes, the slowest return being after the longest compression. Intermittent spontaneous, high-pitched vocalization, associated with vigorous running movements of all 4 limbs, with the dog lying on his side, often occurred during the first few hours.
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